1. Field of the Invention
The present invention relates to a method for supplying fuel to a combustion chamber which comprises (includes, but is not limited to) at least one main injector and at least one pilot injector, with a first flow of fuel being supplied to the pilot injector during start-up of the combustion chamber via a first regulator valve.
The invention also relates to a device for supplying fuel to a combustion chamber which comprises at least one main injector and at least one pilot injector. The device includes a fuel tank, a line system coupled from the fuel tank to the injectors, a pump for pumping fuel from the tank to the injectors, and a first regulator valve for regulating the flow of fuel in a first line in the system which is connected to the pilot injector.
The invention relates particularly to the supply of fuel to a combustion chamber of a gas turbine. In the conventional technology, the combustion chamber comprises a pilot injector which is arranged centrally, and a plurality of main injectors, for example 5, arranged about the pilot injector.
2. Background of the Invention
To start up a cold engine, a flame is ignited with the pilot injector in order to increase the temperature in the combustion chamber so that it is possible to obtain a working flame with the main injectors. When using the main injectors, the fuel is in fact intended to be combusted in evaporated form. To achieve evaporation, the combustion chamber has to be hot. The fuel from the pilot injector, by contrast, is intended to be combusted in liquid form, in the form of droplets. At start-up, a relatively large flow of fuel is supplied to the pilot injector. At intermediate and high load operation, by contrast, the pilot injector is intended to be supplied only with a small flow of fuel, which must nevertheless be sufficient to maintain a flame from the pilot injector and thereby ensure that the main injectors and the combustion chamber do not go out.
According to a previously known fuel supply device, a first regulator valve is used to regulate the flow of fuel to the main injectors and to the pilot injector. The device further includes a pressure regulator for cooperating with the first regulator valve for controlling the flow of fuel to the pilot injector. With this arrangement, however, it has been found difficult to control the flows to the main and pilot injectors in an exact way which, on one hand, prevents extinguishment of the combustion chamber and, on the other hand, ensures that emissions, such as CO, NOx, and uncombusted hydrocarbons, are kept to a low level. The combustion of the fuel in droplet form via the pilot injector is in fact associated with such emissions.